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wireshark/epan/dissectors/packet-pw-satop.c

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/* packet-pw-satop.c
* Routines for SAToP PW dissection as per RFC4553.
* Copyright 2009, Dmitry Trebich, Artem Tamazov <artem.tamazov@tellabs.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*
* History:
* ---------------------------------
* 19.03.2009 initial implementation
* 14.08.2009 added: support for IP/UDP demultiplexing
* Not supported yet:
* - Decoding of PW payload
* - Optional RTP Headers (RFC3550)
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/expert.h>
#include "packet-mpls.h"
#include "packet-pw-common.h"
void proto_register_pw_satop(void);
void proto_reg_handoff_pw_satop(void);
static gint proto = -1;
static gint ett_pw_satop = -1;
static int hf_cw = -1;
static int hf_cw_bits03 = -1;
static int hf_cw_l = -1;
static int hf_cw_r = -1;
static int hf_cw_rsv = -1;
static int hf_cw_frg = -1;
static int hf_cw_len = -1;
static int hf_cw_seq = -1;
static int hf_payload = -1;
static int hf_payload_l = -1;
static expert_field ei_cw_rsv = EI_INIT;
static expert_field ei_payload_size_invalid_undecoded = EI_INIT;
static expert_field ei_payload_size_invalid = EI_INIT;
static expert_field ei_cw_frg = EI_INIT;
static expert_field ei_cw_bits03 = EI_INIT;
static expert_field ei_cw_packet_size_too_small = EI_INIT;
static dissector_handle_t pw_padding_handle;
static dissector_handle_t pw_satop_udp_handle;
static dissector_handle_t pw_satop_mpls_handle;
const char pwc_longname_pw_satop[] = "SAToP (no RTP support)";
static const char shortname[] = "SAToP (no RTP)";
static
void dissect_pw_satop(tvbuff_t * tvb_original
,packet_info * pinfo
,proto_tree * tree
,pwc_demux_type_t demux)
{
const int encaps_size = 4; /*RTP header in encapsulation is not supported yet*/
gint packet_size;
gint payload_size;
gint padding_size;
int properties;
enum {
PAY_NO_IDEA = 0
,PAY_LIKE_E1
,PAY_LIKE_T1
,PAY_LIKE_E3_T3
,PAY_LIKE_OCTET_ALIGNED_T1
} payload_properties;
packet_size = tvb_reported_length_remaining(tvb_original, 0);
/*
* FIXME
* "4" below should be replaced by something like "min_packet_size_this_dissector"
* Also call to dissect_try_cw_first_nibble() should be moved before this block
*/
if (packet_size < 4) /* 4 is smallest size which may be sensible (for PWACH dissector) */
{
proto_item *item;
item = proto_tree_add_item(tree, proto, tvb_original, 0, -1, ENC_NA);
expert_add_info_format(pinfo, item, &ei_cw_packet_size_too_small,
"PW packet size (%d) is too small to carry sensible information"
,(int)packet_size);
col_set_str(pinfo->cinfo, COL_PROTOCOL, shortname);
col_set_str(pinfo->cinfo, COL_INFO, "Malformed: PW packet is too small");
return;
}
switch (demux)
{
case PWC_DEMUX_MPLS:
if (dissect_try_cw_first_nibble(tvb_original, pinfo, tree))
{
return;
}
break;
case PWC_DEMUX_UDP:
break;
default:
DISSECTOR_ASSERT_NOT_REACHED();
return;
}
/* check how "good" is this packet */
/* also decide payload length from packet size and CW */
properties = 0;
if (0 != (tvb_get_guint8(tvb_original, 0) & 0xf0 /*bits03*/))
{
properties |= PWC_CW_BAD_BITS03;
}
if (0 != (tvb_get_guint8(tvb_original, 0) & 0x03 /*rsv*/))
{
properties |= PWC_CW_BAD_RSV;
}
if (0 != (tvb_get_guint8(tvb_original, 1) & 0xc0 /*frag*/))
{
properties |= PWC_CW_BAD_FRAG;
}
{
/* RFC4553:
* [...MAY be used to carry the length of the SAToP
* packet (defined as the size of the SAToP header + the payload
* size) if it is less than 64 bytes, and MUST be set to zero
* otherwise... ]
*
* Note that this differs from RFC4385's definition of length:
* [ If the MPLS payload is less than 64 bytes, the length field
* MUST be set to the length of the PW payload...]
*
* We will use RFC4553's definition here.
*/
int cw_len;
gint payload_size_from_packet;
cw_len = tvb_get_guint8(tvb_original, 1) & 0x3f;
payload_size_from_packet = packet_size - encaps_size;
if (cw_len != 0)
{
gint payload_size_from_cw;
payload_size_from_cw = cw_len - encaps_size;
/*
* Assumptions for error case,
* will be overwritten if no errors found:
*/
payload_size = payload_size_from_packet;
padding_size = 0;
if (payload_size_from_cw < 0)
{
properties |= PWC_CW_BAD_PAYLEN_LT_0;
}
else if (payload_size_from_cw > payload_size_from_packet)
{
properties |= PWC_CW_BAD_PAYLEN_GT_PACKET;
}
else if (payload_size_from_packet >= 64)
{
properties |= PWC_CW_BAD_LEN_MUST_BE_0;
}
else /* ok */
{
payload_size = payload_size_from_cw;
padding_size = payload_size_from_packet - payload_size_from_cw; /* >=0 */
}
}
else
{
payload_size = payload_size_from_packet;
padding_size = 0;
}
}
if (payload_size == 0)
{
/*
* As CW.L it indicates that PW payload is invalid, dissector should
* not blame packets with bad payload (including "bad" or "strange" SIZE of
* payload) when L bit is set.
*/
if (0 == (tvb_get_guint8(tvb_original, 0) & 0x08 /*L bit*/))
{
properties |= PWC_PAY_SIZE_BAD;
}
}
/* guess about payload type */
if (payload_size == 256)
{
payload_properties = PAY_LIKE_E1;
}
else if (payload_size == 192)
{
payload_properties = PAY_LIKE_T1;
}
else if (payload_size == 1024)
{
payload_properties = PAY_LIKE_E3_T3;
}
else if ((payload_size != 0) && (payload_size % 25 == 0))
{
payload_properties = PAY_LIKE_OCTET_ALIGNED_T1;
}
else
{
payload_properties = PAY_NO_IDEA; /*we do not have any ideas about payload type*/
}
/* fill up columns*/
col_set_str(pinfo->cinfo, COL_PROTOCOL, shortname);
col_clear(pinfo->cinfo, COL_INFO);
if (properties & PWC_ANYOF_CW_BAD)
{
col_set_str(pinfo->cinfo, COL_INFO, "CW:Bad, ");
}
if (properties & PWC_PAY_SIZE_BAD)
{
col_append_str(pinfo->cinfo, COL_INFO, "Payload size:0 (Bad)");
}
else
{
col_append_fstr(pinfo->cinfo, COL_INFO, "TDM octets:%d", (int)payload_size);
}
if (padding_size != 0)
{
col_append_fstr(pinfo->cinfo, COL_INFO, ", Padding:%d", (int)padding_size);
}
{
proto_item* item;
item = proto_tree_add_item(tree, proto, tvb_original, 0, -1, ENC_NA);
pwc_item_append_cw(item,tvb_get_ntohl(tvb_original, 0),TRUE);
pwc_item_append_text_n_items(item,(int)payload_size,"octet");
{
proto_tree* tree2;
tree2 = proto_item_add_subtree(item, ett_pw_satop);
{
tvbuff_t* tvb;
proto_item* item2;
tvb = tvb_new_subset_length(tvb_original, 0, PWC_SIZEOF_CW);
item2 = proto_tree_add_item(tree2, hf_cw, tvb, 0, -1, ENC_NA);
pwc_item_append_cw(item2, tvb_get_ntohl(tvb, 0),FALSE);
{
proto_tree* tree3;
tree3 = proto_item_add_subtree(item2, ett_pw_satop);
{
proto_item* item3;
if (properties & PWC_CW_BAD_BITS03) /*display only if value is wrong*/
{
item3 = proto_tree_add_item(tree3, hf_cw_bits03, tvb, 0, 1, ENC_BIG_ENDIAN);
expert_add_info(pinfo, item3, &ei_cw_bits03);
}
proto_tree_add_item(tree3, hf_cw_l , tvb, 0, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(tree3, hf_cw_r , tvb, 0, 1, ENC_BIG_ENDIAN);
item3 = proto_tree_add_item(tree3, hf_cw_rsv, tvb, 0, 1, ENC_BIG_ENDIAN);
if (properties & PWC_CW_BAD_RSV)
{
expert_add_info(pinfo, item3, &ei_cw_rsv);
}
item3 = proto_tree_add_item(tree3, hf_cw_frg, tvb, 1, 1, ENC_BIG_ENDIAN);
if (properties & PWC_CW_BAD_FRAG)
{
expert_add_info(pinfo, item3, &ei_cw_frg);
}
item3 = proto_tree_add_item(tree3, hf_cw_len, tvb, 1, 1, ENC_BIG_ENDIAN);
if (properties & PWC_CW_BAD_PAYLEN_LT_0)
{
expert_add_info_format(pinfo, item3, &ei_payload_size_invalid,
"Bad Length: too small, must be > %d",
(int)encaps_size);
}
if (properties & PWC_CW_BAD_PAYLEN_GT_PACKET)
{
expert_add_info_format(pinfo, item3, &ei_payload_size_invalid,
"Bad Length: must be <= than PSN packet size (%d)",
(int)packet_size);
}
if (properties & PWC_CW_BAD_LEN_MUST_BE_0)
{
expert_add_info_format(pinfo, item3, &ei_payload_size_invalid,
"Bad Length: must be 0 if SAToP packet size (%d) is > 64",
(int)packet_size);
}
proto_tree_add_item(tree3, hf_cw_seq, tvb, 2, 2, ENC_BIG_ENDIAN);
}
}
}
}
/* payload */
if (properties & PWC_PAY_SIZE_BAD)
{
expert_add_info_format(pinfo, item, &ei_payload_size_invalid,
"SAToP payload: none found. Size of payload must be <> 0");
}
else if (payload_size == 0)
{
expert_add_info(pinfo, item, &ei_payload_size_invalid_undecoded);
}
else
{
proto_tree* tree2;
tree2 = proto_item_add_subtree(item, ett_pw_satop);
{
proto_item* item2;
tvbuff_t* tvb;
tvb = tvb_new_subset_length(tvb_original, PWC_SIZEOF_CW, payload_size);
item2 = proto_tree_add_item(tree2, hf_payload, tvb, 0, -1, ENC_NA);
pwc_item_append_text_n_items(item2,(int)payload_size,"octet");
{
proto_tree* tree3;
const char* s;
switch(payload_properties)
{
case PAY_LIKE_E1:
s = " (looks like E1)";
break;
case PAY_LIKE_T1:
s = " (looks like T1)";
break;
case PAY_LIKE_E3_T3:
s = " (looks like E3/T3)";
break;
case PAY_LIKE_OCTET_ALIGNED_T1:
s = " (looks like octet-aligned T1)";
break;
case PAY_NO_IDEA:
default:
s = "";
break;
}
proto_item_append_text(item2, "%s", s);
tree3 = proto_item_add_subtree(item2, ett_pw_satop);
call_data_dissector(tvb, pinfo, tree3);
item2 = proto_tree_add_int(tree3, hf_payload_l, tvb, 0, 0
,(int)payload_size); /* allow filtering */
proto_item_set_hidden(item2);
}
}
}
/* padding */
if (padding_size > 0)
{
proto_tree* tree2;
tree2 = proto_item_add_subtree(item, ett_pw_satop);
{
tvbuff_t* tvb;
tvb = tvb_new_subset_length_caplen(tvb_original, PWC_SIZEOF_CW + payload_size, padding_size, -1);
call_dissector(pw_padding_handle, tvb, pinfo, tree2);
}
}
}
return;
}
static
int dissect_pw_satop_mpls( tvbuff_t * tvb_original, packet_info * pinfo, proto_tree * tree, void* data _U_)
{
dissect_pw_satop(tvb_original,pinfo,tree,PWC_DEMUX_MPLS);
return tvb_captured_length(tvb_original);
}
static
int dissect_pw_satop_udp( tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* data _U_)
{
dissect_pw_satop(tvb,pinfo,tree,PWC_DEMUX_UDP);
return tvb_captured_length(tvb);
}
void proto_register_pw_satop(void)
{
static hf_register_info hf[] = {
{ &hf_cw ,{"Control Word" ,"pwsatop.cw"
,FT_NONE ,BASE_NONE ,NULL
,0 ,NULL ,HFILL }},
{&hf_cw_bits03,{"Bits 0 to 3" ,"pwsatop.cw.bits03"
,FT_UINT8 ,BASE_DEC ,NULL
,0xf0 ,NULL ,HFILL }},
{&hf_cw_l, {"L bit: TDM payload state" ,"pwsatop.cw.lbit"
,FT_UINT8 ,BASE_DEC ,VALS(pwc_vals_cw_l_bit)
,0x08 ,NULL ,HFILL }},
{&hf_cw_r, {"R bit: Local CE-bound IWF" ,"pwsatop.cw.rbit"
,FT_UINT8 ,BASE_DEC ,VALS(pwc_vals_cw_r_bit)
,0x04 ,NULL ,HFILL }},
{&hf_cw_rsv, {"Reserved" ,"pwsatop.cw.rsv"
,FT_UINT8 ,BASE_DEC ,NULL
,0x03 ,NULL ,HFILL }},
{&hf_cw_frg, {"Fragmentation" ,"pwsatop.cw.frag"
,FT_UINT8 ,BASE_DEC ,VALS(pwc_vals_cw_frag)
,0xc0 ,NULL ,HFILL }},
{&hf_cw_len, {"Length" ,"pwsatop.cw.length"
,FT_UINT8 ,BASE_DEC ,NULL
,0x3f ,NULL ,HFILL }},
{&hf_cw_seq, {"Sequence number" ,"pwsatop.cw.seqno"
,FT_UINT16 ,BASE_DEC ,NULL
,0 ,NULL ,HFILL }},
{&hf_payload ,{"TDM payload" ,"pwsatop.payload"
,FT_BYTES ,BASE_NONE ,NULL
,0 ,NULL ,HFILL }},
{&hf_payload_l ,{"TDM payload length" ,"pwsatop.payload.len"
,FT_INT32 ,BASE_DEC ,NULL
,0 ,NULL ,HFILL }}
};
static gint *ett_array[] = {
&ett_pw_satop
};
static ei_register_info ei[] = {
{ &ei_cw_packet_size_too_small, { "pwsatop.packet_size_too_small", PI_MALFORMED, PI_ERROR, "PW packet size (%d) is too small to carry sensible information", EXPFILL }},
{ &ei_cw_bits03, { "pwsatop.cw.bits03.not_zero", PI_MALFORMED, PI_ERROR, "Bits 0..3 of Control Word must be 0", EXPFILL }},
{ &ei_cw_rsv, { "pwsatop.cw.rsv.not_zero", PI_MALFORMED, PI_ERROR, "RSV bits of Control Word must be 0", EXPFILL }},
{ &ei_cw_frg, { "pwsatop.cw.frag.not_allowed", PI_MALFORMED, PI_ERROR, "Fragmentation of payload is not allowed for SAToP", EXPFILL }},
{ &ei_payload_size_invalid, { "pwsatop.payload.size_invalid", PI_MALFORMED, PI_ERROR, "Bad Length: too small", EXPFILL }},
{ &ei_payload_size_invalid_undecoded, { "pwsatop.payload.undecoded", PI_UNDECODED, PI_NOTE, "SAToP payload: omitted to conserve bandwidth", EXPFILL }},
};
expert_module_t* expert_pwsatop;
proto = proto_register_protocol(pwc_longname_pw_satop, shortname, "pwsatopcw");
proto_register_field_array(proto, hf, array_length(hf));
proto_register_subtree_array(ett_array, array_length(ett_array));
expert_pwsatop = expert_register_protocol(proto);
expert_register_field_array(expert_pwsatop, ei, array_length(ei));
pw_satop_mpls_handle = register_dissector("pw_satop_mpls", dissect_pw_satop_mpls, proto);
pw_satop_udp_handle = register_dissector("pw_satop_udp", dissect_pw_satop_udp, proto);
}
void proto_reg_handoff_pw_satop(void)
{
pw_padding_handle = find_dissector_add_dependency("pw_padding", proto);
/* For Decode As */
dissector_add_for_decode_as("mpls.label", pw_satop_mpls_handle);
dissector_add_for_decode_as_with_preference("udp.port", pw_satop_udp_handle);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
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